Hi everyone.. Just working on a '39 sparton, the lobster. I replaced all the caps and the tubes all light up.. There is a very faint hum in the speaker, but when I play with the volume or tone control, I get no static or anything.. I tap the tubes and move them with no clicks or sounds.. Just tested the pin voltage and it's way out of wack... The power transformer is a little rusty and gets warm, but you can still touch it after the radio's been on for 20 min or so.. Wondered if it was the volume pot, but I crossed the three connections with a screwdriver and didn't even get a click.. Did a visual inspection and everything looks really good.. The tone control is also the on off switch and it seems to work fine.. Just wondering if anyone has any ideas.. Voltages are especially bad on the rectifier and driver with the higher voltages being around 100v too high according to spec.. Eg 350v is now reading at 450v.. Wondering if this has anything to do with the lack of sound? Or is it maybe a faulty volume or tone pot..!? Thanks for any ideas..!

With the B+ so high that should tell you there is something not drawing any current. The audio output section demands the most current draw. And you have no sound. Check the voltage from power supply to audio output section for an open like a resistor.

:With the B+ so high that should tell you there is something not drawing any current. The audio output section demands the most current draw. And you have no sound. Check the voltage from power supply to audio output section for an open like a resistor.
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:With the B+ so high that should tell you there is something not drawing any current. The audio output section demands the most current draw. And you have no sound. Check the voltage from power supply to audio output section for an open like a resistor.
:
:
Thanks Warren..! That's awesome.! I'll try that tomorrow and see which one is faulty..! Thank you very much for your answer..! I'm new to all this and sometimes it's hard for me to figure out the problem.. I'll re post with how I made out.. Now that you mention it, there's a larger resistor near the output to the speaker that looks cracked..! Thanks again.!

::With the B+ so high that should tell you there is something not drawing any current. The audio output section demands the most current draw. And you have no sound. Check the voltage from power supply to audio output section for an open like a resistor.
::
::
:Thanks Warren..! That's awesome.! I'll try that tomorrow and see which one is faulty..! Thank you very much for your answer..! I'm new to all this and sometimes it's hard for me to figure out the problem.. I'll re post with how I made out.. Now that you mention it, there's a larger resistor near the output to the speaker that looks cracked..! Thanks again.!

If this helps, the B+ starts at the cathode of the 80 rectifier tube, goes through the field coil (good suspect!), then through the output transformer primary, then to pin 3 of the 6AC5 output tube. The cathode goes directly to ground (center tap of the output traonnsformer) without biasing resistor. It appears the speaker connects to the chassis through a plug, with the output transformer on the speaker, all the B+ goes through that plug. Clean the pins and check solder joints there. Hope this helps,
Lewis
:

:::With the B+ so high that should tell you there is something not drawing any current. The audio output section demands the most current draw. And you have no sound. Check the voltage from power supply to audio output section for an open like a resistor.
:::
:::
::Thanks Warren..! That's awesome.! I'll try that tomorrow and see which one is faulty..! Thank you very much for your answer..! I'm new to all this and sometimes it's hard for me to figure out the problem.. I'll re post with how I made out.. Now that you mention it, there's a larger resistor near the output to the speaker that looks cracked..! Thanks again.!
:
:
:
:If this helps, the B+ starts at the cathode of the 80 rectifier tube, goes through the field coil (good suspect!), then through the output transformer primary, then to pin 3 of the 6AC5 output tube. The cathode goes directly to ground (center tap of the output traonnsformer) without biasing resistor. It appears the speaker connects to the chassis through a plug, with the output transformer on the speaker, all the B+ goes through that plug. Clean the pins and check solder joints there. Hope this helps,
:Lewis
:: Hi Lewis..! Well, you're right on the money.. There's no continuity in the field coil.! You get 5 stars.! Thank you very much for taking the time to look at the schematics as I was a little confused after I checked all the resistors and they were fine.. Now I guess I either dismantle and rewind the field coil, or look for the speaker and coil unit on different web sites..? Maybe I can send the unit away to get it rewound? Anyway, thanks again very much.. If you have any ideas or suggestions that would be amazing as I'm kind of feeling a little lost at this point.. It's really a shame because this is a beautiful radio and the chassis is pretty much perfect now.. Have a great night.!
Kyal.
:

::::With the B+ so high that should tell you there is something not drawing any current. The audio output section demands the most current draw. And you have no sound. Check the voltage from power supply to audio output section for an open like a resistor.
::::
::::
:::Thanks Warren..! That's awesome.! I'll try that tomorrow and see which one is faulty..! Thank you very much for your answer..! I'm new to all this and sometimes it's hard for me to figure out the problem.. I'll re post with how I made out.. Now that you mention it, there's a larger resistor near the output to the speaker that looks cracked..! Thanks again.!
::
::
::
::If this helps, the B+ starts at the cathode of the 80 rectifier tube, goes through the field coil (good suspect!), then through the output transformer primary, then to pin 3 of the 6AC5 output tube. The cathode goes directly to ground (center tap of the output traonnsformer) without biasing resistor. It appears the speaker connects to the chassis through a plug, with the output transformer on the speaker, all the B+ goes through that plug. Clean the pins and check solder joints there. Hope this helps,
::Lewis
::: Hi Lewis..! Well, you're right on the money.. There's no continuity in the field coil.! You get 5 stars.! Thank you very much for taking the time to look at the schematics as I was a little confused after I checked all the resistors and they were fine.. Now I guess I either dismantle and rewind the field coil, or look for the speaker and coil unit on different web sites..? Maybe I can send the unit away to get it rewound? Anyway, thanks again very much.. If you have any ideas or suggestions that would be amazing as I'm kind of feeling a little lost at this point.. It's really a shame because this is a beautiful radio and the chassis is pretty much perfect now.. Have a great night.!
:Kyal.
::
:I think it was blown because the electrolitics were already replaced with ones that were incorrect.. ? Thanks again.!
:

:::::With the B+ so high that should tell you there is something not drawing any current. The audio output section demands the most current draw. And you have no sound. Check the voltage from power supply to audio output section for an open like a resistor.
:::::
:::::
::::Thanks Warren..! That's awesome.! I'll try that tomorrow and see which one is faulty..! Thank you very much for your answer..! I'm new to all this and sometimes it's hard for me to figure out the problem.. I'll re post with how I made out.. Now that you mention it, there's a larger resistor near the output to the speaker that looks cracked..! Thanks again.!
:::
:::
:::
:::If this helps, the B+ starts at the cathode of the 80 rectifier tube, goes through the field coil (good suspect!), then through the output transformer primary, then to pin 3 of the 6AC5 output tube. The cathode goes directly to ground (center tap of the output traonnsformer) without biasing resistor. It appears the speaker connects to the chassis through a plug, with the output transformer on the speaker, all the B+ goes through that plug. Clean the pins and check solder joints there. Hope this helps,
:::Lewis
:::: Hi Lewis..! Well, you're right on the money.. There's no continuity in the field coil.! You get 5 stars.! Thank you very much for taking the time to look at the schematics as I was a little confused after I checked all the resistors and they were fine.. Now I guess I either dismantle and rewind the field coil, or look for the speaker and coil unit on different web sites..? Maybe I can send the unit away to get it rewound? Anyway, thanks again very much.. If you have any ideas or suggestions that would be amazing as I'm kind of feeling a little lost at this point.. It's really a shame because this is a beautiful radio and the chassis is pretty much perfect now.. Have a great night.!
::Kyal.
:::
::I think it was blown because the electrolitics were already replaced with ones that were incorrect.. ? Thanks again.!
::
:Should I just get a magnetic speaker and move the output transformer over to it and run a 1500 ohm (the rating of the field coil) resistor in it's place!? Maybe a 20 w one? Also this might sound dumb.. But why is the field coil also connected into the output transformer.. It has 3 poles not two? Thanks for any explanation, as I am a novice to antique radios and electronics in general.. Although I have re capped and repaired 12 successfully.. Thanks gentlemen.!
Kyal.
:

::::::With the B+ so high that should tell you there is something not drawing any current. The audio output section demands the most current draw. And you have no sound. Check the voltage from power supply to audio output section for an open like a resistor.
::::::
::::::
:::::Thanks Warren..! That's awesome.! I'll try that tomorrow and see which one is faulty..! Thank you very much for your answer..! I'm new to all this and sometimes it's hard for me to figure out the problem.. I'll re post with how I made out.. Now that you mention it, there's a larger resistor near the output to the speaker that looks cracked..! Thanks again.!
::::
::::
::::
::::If this helps, the B+ starts at the cathode of the 80 rectifier tube, goes through the field coil (good suspect!), then through the output transformer primary, then to pin 3 of the 6AC5 output tube. The cathode goes directly to ground (center tap of the output traonnsformer) without biasing resistor. It appears the speaker connects to the chassis through a plug, with the output transformer on the speaker, all the B+ goes through that plug. Clean the pins and check solder joints there. Hope this helps,
::::Lewis
::::: Hi Lewis..! Well, you're right on the money.. There's no continuity in the field coil.! You get 5 stars.! Thank you very much for taking the time to look at the schematics as I was a little confused after I checked all the resistors and they were fine.. Now I guess I either dismantle and rewind the field coil, or look for the speaker and coil unit on different web sites..? Maybe I can send the unit away to get it rewound? Anyway, thanks again very much.. If you have any ideas or suggestions that would be amazing as I'm kind of feeling a little lost at this point.. It's really a shame because this is a beautiful radio and the chassis is pretty much perfect now.. Have a great night.!
:::Kyal.
::::
:::I think it was blown because the electrolitics were already replaced with ones that were incorrect.. ? Thanks again.!
:::
::Should I just get a magnetic speaker and move the output transformer over to it and run a 1500 ohm (the rating of the field coil) resistor in it's place!? Maybe a 20 w one? Also this might sound dumb.. But why is the field coil also connected into the output transformer.. It has 3 poles not two? Thanks for any explanation, as I am a novice to antique radios and electronics in general.. Although I have re capped and repaired 12 successfully.. Thanks gentlemen.!
:Kyal.
::
:
K I'm not going to perform the above procedure as I would like to keep this radio as close to original as possible.. So I'm going to send it to the speaker shop in Ohio and get them to rewind it for me.. Unless anyone else has an idea!?? Cheers.!
Kyal.

:::::::With the B+ so high that should tell you there is something not drawing any current. The audio output section demands the most current draw. And you have no sound. Check the voltage from power supply to audio output section for an open like a resistor.
:::::::
:::::::
::::::Thanks Warren..! That's awesome.! I'll try that tomorrow and see which one is faulty..! Thank you very much for your answer..! I'm new to all this and sometimes it's hard for me to figure out the problem.. I'll re post with how I made out.. Now that you mention it, there's a larger resistor near the output to the speaker that looks cracked..! Thanks again.!
:::::
:::::
:::::
:::::If this helps, the B+ starts at the cathode of the 80 rectifier tube, goes through the field coil (good suspect!), then through the output transformer primary, then to pin 3 of the 6AC5 output tube. The cathode goes directly to ground (center tap of the output traonnsformer) without biasing resistor. It appears the speaker connects to the chassis through a plug, with the output transformer on the speaker, all the B+ goes through that plug. Clean the pins and check solder joints there. Hope this helps,
:::::Lewis
:::::: Hi Lewis..! Well, you're right on the money.. There's no continuity in the field coil.! You get 5 stars.! Thank you very much for taking the time to look at the schematics as I was a little confused after I checked all the resistors and they were fine.. Now I guess I either dismantle and rewind the field coil, or look for the speaker and coil unit on different web sites..? Maybe I can send the unit away to get it rewound? Anyway, thanks again very much.. If you have any ideas or suggestions that would be amazing as I'm kind of feeling a little lost at this point.. It's really a shame because this is a beautiful radio and the chassis is pretty much perfect now.. Have a great night.!
::::Kyal.
:::::
::::I think it was blown because the electrolitics were already replaced with ones that were incorrect.. ? Thanks again.!
::::
:::Should I just get a magnetic speaker and move the output transformer over to it and run a 1500 ohm (the rating of the field coil) resistor in it's place!? Maybe a 20 w one? Also this might sound dumb.. But why is the field coil also connected into the output transformer.. It has 3 poles not two? Thanks for any explanation, as I am a novice to antique radios and electronics in general.. Although I have re capped and repaired 12 successfully.. Thanks gentlemen.!
::Kyal.
:::
::
: K I'm not going to perform the above procedure as I would like to keep this radio as close to original as possible.. So I'm going to send it to the speaker shop in Ohio and get them to rewind it for me.. Unless anyone else has an idea!?? Cheers.!
:Kyal.
:
:
Hi, the field coil also acts as an a filter choke, I have tried the resistor trick and it does work but the results were terrible sounding hum that was prominent especially at lower volume, basically sounded like crap, so i would keep the field coil or try and find a filter choke trans of the same dc resistance and then you could sub with pm speaker.

::::::::With the B+ so high that should tell you there is something not drawing any current. The audio output section demands the most current draw. And you have no sound. Check the voltage from power supply to audio output section for an open like a resistor.
::::::::
::::::::
:::::::Thanks Warren..! That's awesome.! I'll try that tomorrow and see which one is faulty..! Thank you very much for your answer..! I'm new to all this and sometimes it's hard for me to figure out the problem.. I'll re post with how I made out.. Now that you mention it, there's a larger resistor near the output to the speaker that looks cracked..! Thanks again.!
::::::
::::::
::::::
::::::If this helps, the B+ starts at the cathode of the 80 rectifier tube, goes through the field coil (good suspect!), then through the output transformer primary, then to pin 3 of the 6AC5 output tube. The cathode goes directly to ground (center tap of the output traonnsformer) without biasing resistor. It appears the speaker connects to the chassis through a plug, with the output transformer on the speaker, all the B+ goes through that plug. Clean the pins and check solder joints there. Hope this helps,
::::::Lewis
::::::: Hi Lewis..! Well, you're right on the money.. There's no continuity in the field coil.! You get 5 stars.! Thank you very much for taking the time to look at the schematics as I was a little confused after I checked all the resistors and they were fine.. Now I guess I either dismantle and rewind the field coil, or look for the speaker and coil unit on different web sites..? Maybe I can send the unit away to get it rewound? Anyway, thanks again very much.. If you have any ideas or suggestions that would be amazing as I'm kind of feeling a little lost at this point.. It's really a shame because this is a beautiful radio and the chassis is pretty much perfect now.. Have a great night.!
:::::Kyal.
::::::
:::::I think it was blown because the electrolitics were already replaced with ones that were incorrect.. ? Thanks again.!
:::::
::::Should I just get a magnetic speaker and move the output transformer over to it and run a 1500 ohm (the rating of the field coil) resistor in it's place!? Maybe a 20 w one? Also this might sound dumb.. But why is the field coil also connected into the output transformer.. It has 3 poles not two? Thanks for any explanation, as I am a novice to antique radios and electronics in general.. Although I have re capped and repaired 12 successfully.. Thanks gentlemen.!
:::Kyal.
::::
:::
:: K I'm not going to perform the above procedure as I would like to keep this radio as close to original as possible.. So I'm going to send it to the speaker shop in Ohio and get them to rewind it for me.. Unless anyone else has an idea!?? Cheers.!
::Kyal.
::
::
:Hi, the field coil also acts as an a filter choke, I have tried the resistor trick and it does work but the results were terrible sounding hum that was prominent especially at lower volume, basically sounded like crap, so i would keep the field coil or try and find a filter choke trans of the same dc resistance and then you could sub with pm speaker.
:
Thanks Dale..! Ya I'm not going to mess with a replacement speaker to keep the radio as original as possible.! Thanks for the explanation and advice.!

Your field coil also has a separate winding that is used for hum bucking. It takes any AC sign wave and puts it 180 out of phase, then puts it into the audio to cancel out hum.

:Your field coil also has a separate winding that is used for hum bucking. It takes any AC sign wave and puts it 180 out of phase, then puts it into the audio to cancel out hum.
:
:Oh..ok.! That explains a lot to me.. Makes total sense now.. I'm going to keep the speaker original, as it's in great shape in spite of the open field coil.. I'm trying to decide now whether to rewind it myself or have it sent away.. I've never done it and I don't want to mess it up in the middle of fixing it and have to send it to the speaker shop not original and in a shambles.. From what I know, it shouldn't be too hard, it's basically laying the correct number of windings and insulation.. Although it might take some time to make sure it's laid out perfectly.. If anyone has tried this before do they have any tips? Or should I just send it off!? Thanks for the help Warren.!

Some have tried the needle trick. You connect one lead of your ohm meter to the bottom winding of the field coil. The other lead to a sewing needle. Probe the coil with the needle to see if you can find Continuity. If you do then scrape away the enamel coating. Then solder a new lead to that point. This all risky. And not that dependable. If your radio is as good looking as you say.
I would send it off for an overhaul. The Sparton Lobster is one of the high dollar Collectable radios.

:Some have tried the needle trick. You connect one lead of your ohm meter to the bottom winding of the field coil. The other lead to a sewing needle. Probe the coil with the needle to see if you can find Continuity. If you do then scrape away the enamel coating. Then solder a new lead to that point. This all risky. And not that dependable. If your radio is as good looking as you say.
:I would send it off for an overhaul. The Sparton Lobster is one of the high dollar Collectable radios.
:
:Thanks for the great advice Warren.! I will probably do what you say and send the speaker away.. As you stated, it's a very collectible piece..!

Check the cathode resistor for the audio output tube. If this resistor is open, the tube can't sink any current and the tube's plate voltage will be abnormally high. Resistor should be a fairly small value, maybe a couple of hundred ohms or so.

:Check the cathode resistor for the audio output tube. If this resistor is open, the tube can't sink any current and the tube's plate voltage will be abnormally high. Resistor should be a fairly small value, maybe a couple of hundred ohms or so.
:
Thanks Tom.! It ended up being the field coil.. :( that's a little harder to fix but no one ever said this stuff was easy.! Lol.! Thanks for your suggestion an I will remember it for the next radio I work on..!
Kyal.